The invention relates to the field of combinations of surfactants and solvents (surfactant/solvent systems) for liquid formulations of active substances (also referred to as liquid preparations), in particular of agrochemical active substances. The invention preferably relates to surfactant/solvent systems for one-phase formulations of one or more agrochemical active substances, where at least one of the active substances, preferably each active substance, is not readily soluble in water. In particular, the invention relates to emulsifiable concentrates (EC) which are based on organic solvents and agrochemical active substances of different polarity. Formulations in the form of oil-based emulsions or suspension concentrates are also possible, and preference is given specifically to emulsifiable concentrates which may comprise one or more agrochemical active substances from the group of the herbicides, insecticides, fungicides, acaricides, molluskicides, rodenticides and/or timber preservatives. Preferred in this context are, inter alia, beet herbicides such as desmedipham, phenmedipham, ethofumesate, metamitron and herbicides which are of a similar type with regard to their physical and application properties, for example herbicides from the series of the phenoxyphenoxypropionates or of the heteroaryloxyphenoxypropionates.
In general, active substances are employed not as pure materials, but, depending on the field of application and the desired physical composition of the use form, in combination with certain adjuvants, i.e. they are xe2x80x9cformulatedxe2x80x9d. Frequently, such formulations contain combinations of various active substances instead of individual active substances to make use, upon application, of the joint properties of the individual active substances, or else because individual active substances are synergistic in combination, i.e. their action is enhanced in a superadditive fashion.
Independently of the type of formulation and of whether the formulations comprise one or more active substances, the aim in particular in the agricultural sector is to achieve the highest possible active substance concentration (xe2x80x9cloadxe2x80x9d) of the formulation in question, since a high concentration of the active substances permits the application volumes to be reduced, which, as a consequence, saves material with regard to the adjuvants applied and saves costs in the packaging and transport sector.
Highly concentrated stable formulations and coformulations with environmentally friendly adjuvants are therefore interesting as a matter of principle.
In principle, active substances can be formulated in various ways, depending on the biological and/or chemico-physical parameters specified. In general, examples of suitable formulations which are possible are wettable powders (WP), oil-in-water (O/W) or water-in-oil (W/O) emulsions, suspensions (SC), suspoemulsions (SE), emulsifiable concentrates (EC), or else granules for soil application or spreading, or water-dispersible granules (WG). The abovementioned formulation types are known in principle and are described, for example, in: Winnacker-Kxc3xcchler, xe2x80x9cChemische Technologiexe2x80x9d [Chemical Engineering], Volume 7, C. Hauser-Verlag, Munich, 4th Edition 1986; van Valkenburg, xe2x80x9cPesticide Formulationsxe2x80x9d, Marcel-Dekker N.Y., 1973; K. Martens, xe2x80x9cSpray Drying Handbookxe2x80x9d, 3rd Ed., 1979, G. Goodwin Ltd. London.
Liquid formulations of herbicides are already known. Thus, for example, WO-A-85/01286 describes liquid formulations which comprise phenmedipham and/or metamitron. Solvents which are mentioned in this context are esters of polyalcohols, ethers, ketones, water-insoluble alcohols, (poly)glycols and oils of vegetable, but also of mineral, origin, and suitable emulsifiers mentioned only in general for the above-described liquid formulations are nonionic, but also ampholytic, cationic or anionic surfactants.
Suitable alternatives to solvent-based emulsifiable concentrates for the abovementioned active substances are inter alia water-containing suspension concentrates (SC) or suspoemulsions (SE). Such formulations are described, for example, in EP-A 0514769, WO-A-95/23505, EP-A-0637910 and WO-A-92/09195.
FR-A-2597720, FR-A-2599593 and FR-A-2590119 describe emulsifiable concentrates whichxe2x80x94in deviation from the publications cited abovexe2x80x94together with (at least) one herbicide of the biscarbamate type (in particular phenmedipham or desmedipham) comprise a solvent combination of tributyl phosphate and a solvent which is miscible with water, such as, in particular, N-methylpyrrolidone (NMP).
Furthermore, EP-A-0328217 describes emulsifiable concentrates which comprise ethofumesate and, as solvent, tributyl phosphate. The disadvantage in the last-mentioned type of formulation is the use of tributyl phosphate because it is considered to be a dangerous chemical (cf., for example, Chemikaliengesetz [German Chemicals Act]). While this does not make impossible, or ban, the use of tributyl phosphate, the use entails, as a rule, conditions or is generally problematic.
Furthermore, it is known that the biological activity of some pesticidal active substances can be enhanced in some cases by low-molecular weight organic compounds. Thus, in accordance with BE-A-597284, esters or partial esters based on orthophosphoric acid and alkyl-, aryl-, alkylaryl-, cycloalkylaryl- and/or heterocycle-based alcohols are suitable for increasing the action of herbicides, for example herbicidal phenylurea derivatives such as monuron, azoles such as amitrol, triazines such as simazine and propionic acid derivatives such as dalapon. The phosphoric esters specifically described in this context as adjuvants only encompass phosphoric esters which are relatively unpolar or fully soluble in water and which are not suitable for the preparation of emulsifiable concentrates.
DE-A-2914164 describes synergistic effects which are found in the case of herbicides with a desiccant action on crop plants, i.e. for example herbicides from the group of the phenylureas (for example metoxuron, diuron) or triazines (for example atrazine, simazine), when they are combined with phosphorus-based compositions as are employed in industrial metallurgy for obtaining metals or as plasticizers for polymers. It can be seen unambiguously from the publication that these phosphorus-based compositions, which can be employed for example in industrial metallurgy for obtaining metals or as plasticizers in polymers, are employed as active substances in this context and not as solvents. In other words, this means that the phosphoric acid derivatives in this publication are active substances and not solvents or carriers for agrochemical active substances in the traditional sense. It can also be found in the Japanese Patent Specification JA 29878169, that, for example, tributoxyethyl phosphate (TBEP) is described as active substance, but not as solvent.
Surprisingly, it has now been found that certain surfactant/solvent systems are suitable in a particular manner for use in the preparation of liquid formulations such as oil dispersions, suspoemulsions, W/O- or O/W-based emulsions and, in particular, of emulsifiable concentrates and corresponding aqueous spray mixtures derived therefrom.